Rotors powered by flowing current consist generally of two types, those with axis of rotation parallel to the current and those with axis of rotation perpendicular to it. Rotational energy is supplied around a central shaft (axis of rotation) in both types of a series of identical vanes radially extending from the shaft at uniform intervals around the circumference.
An airplane propeller is a rotor of the first type, having its rotational axis parallel to the current. the vanes of this type of rotor are angled (pitched) on their radial axis relative to the axis of rotation to provide rotational thrust.
Current force vectors applicable to a particular point on a given vane are generally constant throughout their circular revolution of the shaft. Nearly identical force vectors affect corresponding points on the other vanes.
These types of rotors have been equipped with variable pitch vanes as shown in U.S. Pat. No. 400,209 wherein the pitch of all vanes against the current can be adjusted to optimize performance at different rotational speeds and the like. The vanes of such rotors can be curved as in a spiral to better capture fluid flow while imparting rotational effect and the spiral can even be made continuous around the length of the shaft as shown in U.S. Pat. No. 1,071,748.
Rotors axially oriented with the current have a continuous power cycle imparted by one side only of the vanes.
The other main type of rotor, i.e. one axially oriented against the current, has a two-part cycle effected by each vane, a power stroke and a return. The series of identical vanes are mounted parallel to the rotational axis and are perpendicular to the current with one side at the mid-point of the power stroke and with the other side at the mid-point of the return stroke. These paddle wheel type rotors have traditionally been oriented in supporting structures such that a current stream impinges only a portion (less than half) of the rotor to drive it as in the general use of paddle wheels having a lower portion in a water current and the upper portion held in the air above the water surface. This method is shown by the tidal motor of U.S. Pat. No. 700,408 and the wave motor of U.S. Pat. No. 1,289,533.
Various means are shown in the art for directing or channelling current against rotors or portions thereof. U.S. Pat. No. 757,909 shows a portable spillway and U.S. Pat. No. 946,104 shows a portable chute having such purpose.
The art of mounting rotors on floating platforms to generate electrical power from river current is known as shown in U.S. Pat. No. 1,147,658.
Prior art does not disclose hinged or flappable vanes for application with cross-current rotors whereby the vanes are automatically extended in their power stroke by current against one side to receive maximum current force against that side during power cycle and retracted by current force against the other side during the return cycle to receive a reduced current force against that side. Such hinged vane rotors can fill a need for improvement in cross current rotor technology and should be useful in filling many needs for such rotors, particularly for low cost, easily erected hydroelectric generating facilities.